People are fond of defining art in ways that exclude things they disapprove of. But this makes the task of coming up with a universally acceptable definition of art even harder than it already is. A conscientious objection to ivory sculpture is fine - don't carve any ivory, don't purchase any ivory statuary, close your eyes in certain sections of the Asian art museum - but redefining art to debar certain materials is problematic.
Many materials are sourced in ways that harm the earth's ecology in one way or another - hardly any can be said to be totally environmentally benign. Where do you draw the line? Are sculptures made from gold still art? Or do they have to be made from post-consumer waste to qualify? How do you define art in a way that accommodates your scruples? Do you have to approve of everything about it in order for any sculpture to count as art for the rest of us? Or is your definition of art just for you?